Various types and configurations of prosthetic heart valves are used to replace diseased natural human heart valves. The actual shape and configuration of any particular prosthetic heart valve is dependent to some extent upon the valve being replaced (i.e., mitral valve, tricuspid valve, aortic valve, and pulmonary valve). In general terms, however, most prosthetic heart valve designs attempt to replicate the function of the valve being replaced and thus will include valve leaflet-like structures.
As used throughout this specification a “prosthetic heart valve having relatively flexible leaflets” or a “prosthetic heart valve” is intended to encompass bioprosthetic heart valves having leaflets made of a biological material as well as synthetic heart valves having leaflets made of a synthetic (e.g., polymeric) material. Either type of prosthetic heart valve can include a frame or stent or may have no such frame or stent. A stented prosthetic heart valve typically includes a stent having a substantially circular base (or stent ring), around which an annular suture material is disposed for suturing the prosthesis to heart tissue. The stent further typically includes at least two, but typically three, support structures extending from the stent ring. These support structures are commonly referred to as stent posts or commissure posts. These posts typically are rigid yet somewhat flexible structures extending from the stent ring, which are covered by a cloth-like material similar to that of the annular suture material or tissue. The stent or commissure posts define the juncture between adjacent tissue or synthetic leaflets otherwise secured thereto. Examples of bioprosthetic heart valves are described in U.S. Pat. No. 4,106,129 (Carpentier et al.), and U.S. Pat. No. 5,037,434 (Lane), the entire disclosures of which are incorporated herein by reference. These disclosures detail a conventional configuration of three leaflets, with one leaflet disposed between each pair of stent or commissure posts.
Implantation of a stented prosthetic heart valve presents certain technical challenges. For example, a prosthetic mitral valve is normally implanted by placing the prosthesis into the mitral valve annulus with the stent posts projecting blindly deep into the patient's left ventricle. However, due to a lack of visibility through the prosthetic valve, a surgeon can inadvertently loop sutures around the stent posts during suturing of the annular suture ring portion of the prosthesis. Similarly, the extending stent posts may undesirably “snag” on chordae or trabeculae inside the left ventricular cavity. To avoid these complications, various prosthetic valve holders have been designed that inwardly retract or deflect and hold the mitral prosthetic stent posts during implantation. Some of the available prosthetic mitral heart valve holders include an elongated handle and a holder mechanism that is secured to the stent ring and adapted to inwardly deflect the stent posts upon rotation of the handle. An exemplary prosthetic mitral heart valve holder is described in U.S. Pat. No. 4,865,600 (Carpentier et al.), the entire contents of which is incorporated herein by reference. In addition, these concepts can apply to a prosthetic tricuspid valve.
For another example, Medtronic mitral valves are commercially available under the trade designation “Hancock”, which valves are mounted to a holder providing a mechanism for inward deflection, as illustrated in the brochures: “A New Dimension—The Hancock II Bioprosthesis”, Medtronic Inc., 1991, publication number UC8903226EN and “A New Light on the Hancock Bioprosthesis”, Medtronic Inc., 1988, publication number UC8801713EN, both of which are incorporated herein by reference in their entireties. The type of holder described in these publications includes a ratcheting spool attached to the inflow aspect of the valve opposite the stent posts that is rotatable by means of an attached handle to coil lengths of suture, thereby pulling sutures that extend toward the outflow aspect of the valve, through the commissure posts and between the commissure posts, to thereby deflect the commissure posts inward. In general, these prosthetic mitral heart valve holder devices are well-suited for mitral valve replacement because the mitral valve surgical site is relatively easily accessed, with minimal anatomical obstructions on the inflow aspect of the valve. Thus, the surgeon is afforded a large, unobstructed area for locating and maneuvering the handle as well as performing necessary procedural steps (e.g., suturing the annulus suture ring to the heart tissue) with minimal or no interference from the handle and/or mechanism.
Aortic and pulmonic prosthetic heart valve implantation, however, presents different constraints from those associated with mitral or tricuspid valve replacement because there is less room for the surgeon to maneuver during the surgery. With the increased use of minimally invasive heart valve surgery and depending on the type of thoracotomy performed, the surgeon may first have to pass a prosthesis through a small incision in the chest wall of the patient, either through the sternum or between the ribs. Additionally, depending upon the type of aortotomy performed, the surgeon may have to pass the prosthesis through the sinotubular junction, which is typically smaller than the tissue annulus onto which the prosthetic heart valve will be sutured. Because the stent posts extend proximally toward the surgeon in aortic and pulmonic valve replacement (as opposed to the distal stent post direction associated with mitral and/or tricuspid valve replacement), the chances of inadvertently looping sutures about stent post(s) is minimal. However, the proximally extending stent posts associated with the stented prosthesis still can interfere with the various other maneuvers required of the surgeon.
In light of the above, it can be desirable to inwardly deflect the stent posts during implantation of the aortic and/or pulmonic prosthetic heart valve. Unfortunately, the above-described mitral and tricuspid prosthetic heart valve holders are of little value for aortic and pulmonic valve replacement procedures in that these holders position the holder and handle to extend in a direction opposite from that of the stent posts. As such, the holder and handle would have to be removed in order to implant the aortic prosthetic heart valve. Certain approaches have been taken to correct this incompatibility by reconfiguring the holder and handle to extend in a direction similar to the stent posts on the outflow side of the valve, as described, for example, in U.S. Pat. No. 5,476,510 (Eberhardt et al.) and U.S. Pat. No. 5,716,410 (Eberhardt et al.), the entire disclosures of which are incorporated herein by reference.
There is a continued need to provide different devices for assisting in the implantation of stented prosthetic heart valves that can be used in any area of the heart, including devices that can be used for implantation of aortic prosthetic heart valves. In particular, a need exists for a stent post deflection device that is simple and effective to use for areas of the heart that are typically difficult to access by the surgeon, such as for aortic heart valve replacement.